Engine control systems may include misfire detection modules for identifying combustion events that occur outside of a base ignition timing. As an example, engine misfire can be identified by detecting the fluctuations in the crankshaft torsional vibration. These crankshaft torsional vibrations include the torsional fluctuations in the crankshaft rotation around the mean crankshaft speed.
One example approach is shown by Stander in U.S. Pat. No. 5,633,456. Therein, crankshaft rotation is sampled for a predefined angular displacement for each expected cylinder firing. Misfire signals are then identified by applying filters in the frequency domain.